Physiological and biochemical changes during flower senescence of herbaceous peony and a new postharvest approach for extending flower longevity

The herbaceous peony is a significant cut-flower plant cultivated worldwide. However, the in-depth understanding of herbaceous peony flower senescence is scarce, and the short natural florescence substantially restricts its industrial development. In this study, we investigated the physiological and biochemical responses of 25 different cultivars of herbaceous peony during flower senescence and developed a new postharvest preservation approach to extend flower longevity. We found that herbaceous peony can be divided into three types based on the pattern of ethylene production: the climacteric type, the non climacteric type, and the type with a later-stage increase. In the climacteric type, abscisic acid (ABA) may play a role in triggering ethylene biosynthesis, while in the other two types, ABA had no direct correlation with ethylene biosynthesis. The soluble sugar and protein content were positively correlated with the ABA content. Moreover, total phenolics were highly involved in antioxidant activity, while flavonoids were partially involved. The activities of PPO, POD, SOD, CAT, the MDA content, and the membrane permeability were related to the degree of senescence. We found that silencing senescence-associated transcription factors with virus-induced gene silencing technology (VIGS) and using a vase solution can both extend herbaceous peony flower longevity. Therefore, we construct a new postharvest preservation approach that combines the optimization of VIGS and the use of the vase solution. The new approach can extend the flower longevity of herbaceous peony upto 1.3 times its original lifespan. Our results provide new insights into delaying herbaceous peony flower senescence.